<template>
 <div class="pagination">
    <button @click="$emit('currentPage',pageNo-1)" :disabled="pageNo == 1">上一页</button>
    <button v-if="startAndEndNum.start >= 2" @click="$emit('currentPage',1)">1</button>
    <button v-if="startAndEndNum.start >= 3">···</button>

    <button v-for="(page,index) in startAndEndNum.end" :key="index" v-if="page>=startAndEndNum.start" :class="{active:pageNo==page}" @click="$emit('currentPage',page)">{{page}}</button>
    
    <button  v-if="startAndEndNum.end < totalPage - 1">···</button>
    <button  v-if="startAndEndNum.end < totalPage" @click="$emit('currentPage',totalPage)">{{totalPage}}</button>
    <button @click="$emit('currentPage',pageNo+1)" :disabled="pageNo==totalPage">下一页</button>
    
    <button style="margin-left: 30px">{{total}}</button>
  </div>
</template>

<script>
export default {
    name:'Pagination',
    props:['total','pageNo','pageSize','continues'],
    computed:{
        // 一共多少页
         totalPage(){
            return Math.ceil(this.total/this.pageSize)
         },
        //  连续页码的起始数字和结束数字
        startAndEndNum(){
            let {pageNo,totalPage,continues} = this
            let start = pageNo - parseInt(continues/2);
            let end = pageNo + parseInt(continues/2)
            if(start < 1){
                start = 1;
                end = continues;
            }
            if(end > totalPage){
                end = totalPage;
                start = totalPage - continues + 1;
            }
            return {start,end}
        }
    }
}
</script>

<style lang="less" scoped>
 .pagination {
     text-align: center;
    button {
      margin: 0 5px;
      background-color: #f4f4f5;
      color: #606266;
      outline: none;
      border-radius: 2px;
      padding: 0 4px;
      vertical-align: top;
      display: inline-block;
      font-size: 13px;
      min-width: 35.5px;
      height: 28px;
      line-height: 28px;
      cursor: pointer;
      box-sizing: border-box;
      text-align: center;
      border: 0;

      &[disabled] {
        color: #c0c4cc;
        cursor: not-allowed;
      }

      &.active {
        cursor: not-allowed;
        background-color: #409eff;
        color: #fff;
      }
    }
  }
</style>